Dam and method of constructing the same



June 9, 1931. F. A. NOETZLI I DAM AND immon OF CONSTRUCTING THE sum Filed larch 15, 1928 INVENTOR Patented June 9, 1931 FRED A. NOETZLI, 015 LOS ANGELES, CALIFORNIA DAM AND METHOD OF CONSTRUCTING THE SAME Application filed March 15, 1928.

This invention relates to the construction of concrete and masonry dams of the arched type and the primary object of the-invention is to provide a dam of this type which will be less expensive and which can be built in a shorter period of time than dams such as here'- tofore constructed.

Under the pressure of the water an arched dam is deflected in a down-stream direction. This deflection involves generally large bending moments in the horizontal arches as well as in the vertical cantilevers. The thicker and therefore the stifier these arches and cantilevers are relative to the span and height, the greater are ingeneral the bending moments and the corresponding stresses. 7

In Fig. 3 of the Patent No. 1,410,217 granted to me March 21, 1922, a joint is shown in an arch dam which has a similar function as the corresponding device described in the present specification and in the appending claims. However, the joint shown in Fig. 3

of the Patent No. 1,410,217 is located in the lower portions of the dam only and has the definite function of reducing the cantilever stresses near the base of the dam. It will be observed, however, that any movement of the portions of the dam on opposite sides of the joint will tend to produce heavy shearing stresses at the upper end of the joint which necessitates the placing of steel reinforcement in the dam in this region in order, to prevent the concrete from cracking.

In my improved dam the oint extends upward'to the down-stream face of the dam which makes steel reinforcement along the upper end of the joint generally unnecessary. This arrangement permits also of an unfailing draining of the joint and has other advantages as pointed out subsequently.

The objects of my invention are, first, to build a dam of the arched type in which the arches and cantilevers are made more flexible than they would ordinarily be by dividing them into a plurality of laminae separated by joints; second, to extend these joints from the base of the laminae to the top of the dam or at least to the intersection with the down stream face; third, to provide a water-proofing membrane in one or more of the joints:

Serial No. 261,979.

and fourth, to build the dam in steps by raising the individual laminae alternately. Other objects of my invention will be pointed out subsequently.

In the accompanyingdrawings in which my improved dam is illustrated.

Figure 1 is an elevation of the dam;

Figure 2 is a typical vertical section through the dam;

Figure 3 is a typical horizontal section through the dam;

Figure 4 is a typical section through the center of the dam. 7

Referring to Figure 1: The dam shown comprises an archA spanning between the abutments B. The arch A comprises two arch laminae, an Lip-stream arch 1 and a downstream arch 2. There is a continuous joint 3 between the arches 1 and 2.

Figure 2 is a vertical section along the line 22 of Fig. 1. The joint 3 is shown to extend from the bottom of the two arches 1 and 2 upward to the intersection with the down stream face of the dam. For the purpose of analysis and to facilitate describing the structural behaviour of an arch dam, such a structure is usually assumed as consisting of a series of elementary horizontal arches and a series of vertical cantilevers. Figure 2 illus trates the vertical cantilever laminae C and D of the dam, and it is of importance to note thatthe joint 3 separates not only the two arches 1 and 2 but at the same time the two vertical cantilever laminae C and D. It is of advantage to make the down-stream cantilever lamina D somewhat thicker than the up-stream lamina C in the vicinity of the base of the dam, order to make the downstream lamina D relatively stiffer in a vertical direction than the upstream lamina C. In Fig. 2 are also shown the axes 4; and 5 of the two cantilever laminae C- and D. These axes form an acute angle with each other. 7

Figure 3 is a typical horizontal section along the lines 33 of Fig. 1.. The two arch laminae 1 .and 2 are shown separated by the joint 3 which extends substantially from abutment to abutment ofthe arch A. In case that the arch A is of a uniform thickness in horizontal planes the oint 3 is preferably placed approximately concentric with the surfaces of the arch. A. In case that the arch A is thicker at the abutments than at the crown, for instance, as shown by Fig. 3, the up-stream arch 1 is preferably also thicker at the abutments than at the crown. There are vertical radial joints 6 in the up-stream arch 1, and similar joints 7 in the downstream arch 2. The joints 6 are preferabl olf-set laterally with regard to the joints l.

One of the main objects of the joint 3 is to make the horizontal and vertical elements of the dam more flexible. This hasthe effect of decreasing the rib-shortening and temperature stresses in the arches. The flexibility of the vertical cantilever laminae is also greatly increased by the joint 3. Thus, for a certain load on a vertical element of the dam the deflection is increased approximately four times by the use of a joint 3 over that of the same vertical element having no joint. Thus, a larger percentage of the water load is supported by themuch more economical arch action, and the stresses in the vertical elements are greatly reduced. In Fig. 3 are further shown reinforcing steel bars 8 crossing the plane of the joint These bars 8 will tend to equalize the stresses at the junction of the two laminae and prevent cracking of the concrete. j 7

lVhen the arches 1 and 2 deflect under the water load, the up-stream arch 1 will have compression at a point X at the intrados near the abutments. The down-stream arch 2 will have much less compression, and possibly tension at the point Y opposite point X at the extrados of the down-stream arch 2. Consequently there will be the tendency of a movement in opposite directions of the point X relative to the point Y. In order to permit such a movement which is an essential feature of my improved dam, the friction in the joint 3 must be as small as practicable. In my improved dam the joint 3 is specially prepared for such a purpose by smoothing the surface of theconcrete, or by painting the same with asphalt or other suitable sub stances. I may also provide a waterproofing membrane applied to the extrados of the down-stream arch 2. 'Besides lubricating the joint 3 this membrane will have the most desirable eifect of preventing any water from percolating from the reservoir to the down-stream face of the dam. All water percolating to the joint 3 may be drained by means of special drain pipes 9 and carried through a tunnel 10 or other drains 11 to the down-stream side of the dam. Water seeping into the joint 3 would do no damage even if permitted to rise to the crest ofthe down-stream arch 2 where it couldbe drained off by pipes 12 as shown in Fig. 1. Other- '5 wise'it would flow away by itself and thus prevent the down-stream arch 2 of ever having to support more direct water pressure than with water to its top.

The horizontal arch laminae and vertical cantilever laminae of my improved dam have an area of substantially loose contact between two adjoining laminae, and the extrados of the down-stream arch 2 is substantially in contact with the intrados of the up stream arch 1, except for the waterproofing or other material in the joint 3.

Figure 4 is a vertical section along the line 44 of Fig. 1. In Fig. 4 are shown a plurality of cantilever laminae C and D with joints 3.

In constructing my improved damImay build first the down-stream arch 2 to a certain height, then I prepare the extrados of arch 2 in a suitable manner so as to prevent adhesion of concrete to said extrados. Then I build the up-stream arch 1 by pouring the concrete against the extrados of the downstream arch 2.

Before building theup-stream arch I may first waterproof the extrados of the downstream arch 2. I may also place drain pipes 9 approximately in the plane of the joint 3 and provide an outlettunnel 10 or a drain pipe 11 leading to the down-stream face of the dam.

I use suitable construction methods for building a plurality of arch laminae 1 and 2, with joints 3 between said laminae for the purpose of enabling a relative movement taking place between each two adjacent lam- 1nae.

Thus, I may construct my improved dam by placing and holding in place during concreting a continuous sheet of elastite, tar paper, asphalted burlap or other suitable material for awaterproofing or lubricant in the proper position and then pouring concrete on both sides of said sheet. This sheet will prevent bonding of the concrete and thus form a joint 3 parallel and between the arch laminae 1 and 2 of my improved dam.

In some cases the joint 3 will start at the base of the dam; in other cases it may start higher up.

I claim: I

1. An arch dam comprising a plurality of arch lamina, and an area of substantially loose contact between two adjoining said laminae, said area extending-upward from the bottom of said laminae to the downstream face of said dam.

- 2. In an arched dam between abutments the combination of an upstream arch and a down-stream arch, the extrados 'of the downstream arch being in contact with the intrados of the up-stream arch, said arches being otherwise independent of each other except near said abutments. V

. 3. In an arched dam as described in claim 2, the additional provision of a lubricant between said arches tending to facilitate the movement of said arches relatively to each other.

4. In an arched dam as described in claim 2, the additional provision of drains for car rying away any excess water that might tend to accumulate between said arches.

5. In an arched dam as described in claim 2, the extrados of said down-stream arch being provided with a water-proofing material.

6. In an arched dam supporting water' pressure, the combination of a plurality of cantilever laminae, two of said cantilever laminae being separated by a joint of curved contour extending substantially from the bottom of said laminae upward to the clownstream face of said dam, a water-proofing material in said joint, and suitable means for disposing of excess waters that may tend to accumulate in said joint.

7. In a concrete arched dam stressed by water pressure the combination of an upstream arch lamina and a down-stream arch lamina supported by abutments, with a joint between said laminae, said joint extending from the base of said laminae upwards to the down-stream face of the dam, a lubricating material in said joint for facilitating a relative movement of certain portions of said arch laminae with regard to each other in such a manner that the concrete near said abutments is stressed relatively more near the intrados of said up-stream lamina than near the extrados of said downstream lamina when the water pressure on the dam is increased.

8. In an arched concrete dam the combination of two laminated vertical cantilevers with a joint between said cantilevers extending from the base of said cantilevers upward to the intersection with the down-stream face of said dam, suitable means for reducing the friction in said joint such as to increase the flexibility of said dam in a vertical direction.

9. An arch dam between abutments, said dam comprising two arch laminae and a joint between said laminae extending between said abutments, and reinforcing bars extending across the plane of said joint so as to confine the extension of said joint between such limits as may be desired.

10. In an arched dam the combination of an tip-stream and a down-stream arch lamina, with substantially radial oints in said laminee, said joints in said down-stream lamina beingdisposed laterally relative to the said joints in said up-stream lamina.

11. In a dam an arch between two abutments, a joint dividing said arch into an upstream arch and a clown-stream arch, the up-stream arch being thicker near the abutments than near the crown of said arch.

12. In an arched dam the combination of an up-stream and a down-stream cantilever lamina separated by a joint, said down-stream lamina in the vicinity of the base of said dam being thicker than said up-stream lamina.

13. In an arched dam the combination of two cantilever laminae with a joint between said laminae, said joint extending from the base of said laminae upward to the downstream face of said dam, the axes of said cantilever laminae forming an acute angle with each other.

14. The method of constructing a concrete arch dam comprising an upstream and a downstream arch with a joint between said arches, by building said dam to a certain height, then placing a sheet of material extending upwardly in the direction of said joint, and then pouring concrete substantially simultaneously on both sides of said sheet.

15. The method of constructing a concrete arched dam comprising an upstream and a downstream arch with a joint between said arches, by building said dam to a certain height, then placing a sheet of material extending upwardly in the direction of said joint and providing drainage means alongside of said sheet, and then pouring concrete substantially simultaneously on both sides of said sheet.

16. An arch dam comprising an upstream and a downstream arch extending between abutments, the extrados of the downstream arch being substantially in contact with the intrados of the upstream arch, one of said arches being of non-uniform thickness between the crown and the abutments.

17. The method of constructing a concrete arched dam comprising an upstream and a downstream arch with a joint extending upwardly between said arches, there being a sheet of material in said joint, by constructing said dam to a certain elevation, then extending said sheet upwardly in the direction of said joint, and then placing concrete on both sides of said sheet.

18. In an arched dam comprising a plurality of cantilever elements arranged one behind the other in an upstream and downstream direction, an area of substantially loose contact between at least two adjoining said'elements, said area extending from the base of said elements upward to the clownstream face of said dam.

19. In an arched dam the combination of a plurality of cantilever elements arranged one behind the other in an upstream and downstream direction, two adjoining said elements being separated by a joint extending substantially from the base of said elements upward to the downstream face of said dam, and a water-proofing material in said joint.

FRED A. NOETZLI. 

